The present disclosure relates to an abnormality detection method and an abnormality detection device for an image forming apparatus and to an image forming apparatus, and particularly relates to a method for detecting breakage or positional deviation in a heating belt.
As a fixing unit for use in an electrophotographic image forming apparatus, a thermal belt fixing unit has been known. In the thermal belt fixing unit, a heating belt is looped around a heating roller and a fixing roller. However, in the thermal belt fixing unit, when the heating belt meanders, there is a probability that an abnormality, such as formation of wrinkles in the heating belt, occurs.
In view of the above, a method for judging an abnormality in a fixing belt (heating belt) using a temperature sensor, for example, has been proposed. In such a method, the temperature sensor is provided at an end portion of the heating belt. When the temperature detected by the temperature sensor temporarily decreases, it is determined whether or not the decrease of the temperature is greater than a reference temperature decrease. When decrease of the temperature which is greater than the reference temperature decrease periodically occurs multiple times, it is determined that the heating belt has deformed.